Merge pull request #12 from marcin-lawrowski/feature/clearStack

Added clearing method
Thanks for your contribution!

Backbone.Undo.js

@@ -747,6 +747,15 @@
 		 */
 		removeUndoType: function (type) {
 			manipulateUndoType(2, type, undefined, this.undoTypes);
+		},
+
+		/**
+		 * Removes all actions from the stack.
+		 * @return {undefined}
+		 */
+		clear: function() {
+			this.stack.reset();
+			this.stack.pointer = -1;
 		}
 	});
 

README.md

@@ -204,6 +204,10 @@ This changes an UndoType only on this specific undo manager and won't affect oth
 
 This removes an UndoType only from from this specific undo manager. See the UndoTypes-API for a more thorough documentation on this function.
 
+#### clear              `undoManager.clear()`
+
+This removes all actions from the stack of actions.
+
 ***
 
 Methods you can call on the object `Backbone.UndoManager`:

Tests/Backbone.Undo.Tests.js

@@ -272,6 +272,40 @@ test("Merging UndoManagers", 2, function () {
 	deepEqual(main.stack.at(1).toJSON().after, {"t": 2}, "The main undomanager can still write on its own stack")
 })
 
+test("Clearing all actions", function () {
+	var model = new Backbone.Model({
+		"t": 1
+	});
+
+	var UndoManager = new Backbone.UndoManager({
+		track: true,
+		register: model
+	});
+
+	model.set("t", 2);
+	model.set("t", 3);
+	model.set("t", 4);
+
+	UndoManager.clear();
+
+	UndoManager.undo();
+
+	deepEqual(model.toJSON(), {"t": 4}, "Clearing actions before undoing was successful");
+
+	model.set("t", 2);
+	model.set("t", 3);
+	model.set("t", 4);
+
+	UndoManager.undo();
+	UndoManager.undo();
+
+	UndoManager.clear();
+
+	UndoManager.redo();
+
+	deepEqual(model.toJSON(), {"t": 2}, "Clearing actions before redoing was successful");
+})
+
 /**
  * Async tests for magic condensation
  */